Across the Universe: The Latest News in Space Imaging

Astronomy pictures from the January 2012 AAS Meeting

Twice a year, the American Astronomical Society holds a big meeting where thousands of professional astronomers get together to talk about the latest results and ongoing work in the field. The January meeting is traditionally very well-attended, and is also when a lot of big news is released.

The January 2012 meeting was in Austin, Texas. Even though I couldn't make it this year, I was inundated with news from the event, so much so that I couldn't really keep up. So I figured it would be fun to take some of the best pictures from news items and write up a brief description for a gallery.

At the bottom of each picture is a link labeled "Original Source"; click that to get the full story with all the gory and glorious technical details of the news. You can use the arrows to navigate the pictures, or click them to go to the next in the series. Enjoy!

Dust bunnies in the Milky Way's companion

The Large Magellanic Cloud is a dwarf galaxy that orbits our Milky Way at distance of roughly 160,000 light years. It can be seen by the naked eye from the southern hemisphere... but not like this! Combining images from ESA's Herschel observatory with NASA's Spitzer Space Telescope, this image shows the incredibly complex system of dust in the galaxy glowing in the far infrared.

Bright clumps are where stars are forming; the big one on the left is the Tarantula Nebula, one of the largest and most active stellar nurseries known. However, there are many places where stars are being churned out in the LMC, which is one of the reasons astronomers study it so intently.

El Gordo, a cluster halfway across the Universe

A combination of observations using the orbiting Chandra X-Ray Observatory and the ground-based Very Large Telescope and Atacama Cosmology Telescope has found the largest galaxy cluster ever seen in the distant Universe. They've nicknamed it El Gordo, meaning the fat man in Spanish.

It's actually the result of two clusters colliding. The image is dominated by X-rays (colored blue in the picture) being emitted by gas heated to millions of degrees by the collision. The cluster was found in a survey of how matter distorts the light from the far more distant background glow of the sky emitted by the Big Bang itself. They knew the cluster was big, and when they pointed Chandra at it they knew it was terribly hot from the collision as well. The most amazing thing is its distance: seven billion light years! Knowing how clusters behave at such huge distances helps astronomers understand how the Universe has changed over time, and how the largest structures in the cosmos came to be.

The Universe in super-high-energy

The kind of light we see is called optical light. It's actually rather low energy, emitted by hot things like the Sun, gas clouds, and so on. But what if we could see light that had energies millions of times higher? Billions?

Then the sky would look like this: a map from NASA's Fermi telescope, which sees in gamma rays. Sources of gamma rays are among the most violent in the Universe: exploding stars, fiercely magnetic neutron stars, black holes gobbling down matter. Fermi just completed its third year in space, surveying the entire sky and building up a large and sensitive database of this highest-energy form of light. While many of the individual sources are identified, as many as one third of all the objects in this map cannot be determined.

And that line across the middle? That's our own galaxy, the Milky Way. It's a flat disk, and we're inside it, so we see it as a broad line across the sky. It takes a dark night to see the faint milky band of the galaxy to the naked eye, giving no real hint of the vast and terrible forces at play there. Only by examining the sky in other energies do we start to unveil the true nature of the Universe.

X marks the Swan

4500 light years away in the direction of the constellation of the swan, Cygnus X is a sprawling star-forming region. This infrared image by NASA's Spitzer Space Telescope shows huge, complex structures carved by the fierce winds and light of newborn massive stars. Cavities are dug out, long finger-like tendrils formed, and filaments compressed by these forces, which glow in the IR. Eventually, many of the stars born here will explode, compressing the gas and dust further, in turn creating even more stars. It's the cycle of life, written in cosmic material dozens of light years across.

An incredibly distant galaxy collective

Looking at random parts of the sky with Hubble, astronomers have found what appears to be the most distant protocluster ever seen: five galaxies in the process of growth, forming a cosmic collection that may grow into a massive cluster. The project, called the Brightest of Reionizing Galaxies (BoRG! ha!) survey, examined many images from Hubble. The galaxies are incredibly faint to the eye -- you'd have a hard time seeing them in the image without their locations marked -- but are intrinsically incredibly bright. They're located at a distance of something like 13.1 billion light years away! That means they were forming shortly after the Universe itself did, 13.7 billion years ago!

It's not yet confirmed if the five galaxies are bound together by gravity; the method used to get their distances isn't accurate enough. They'll need to follow up with spectroscopic observations to find that out. If they are connected gravitationally, then they will eventually form the core of a massive cluster of galaxies like the nearby Virgo Cluster, which boasts 2000 members. But as we see them back then, when the Universe itself was so young, they are still just in the process of initial growth (each is smaller than the Milky Way).

And how do they grow? By assimilating material around them. This is how the BORG cluster grows.

Downtown Andromeda

The Andromeda Galaxy is a big, splashy spiral galaxy, the largest one nearby (less than 3 million light years away - that's close as galaxies go). Like every major galaxy, it has a supermassive black hole in its core -- specifically, Andromeda's has a hefty 100 million times the mass of the Sun, making it far larger than our own Milky Way's 4 million mass central black hole.

You'd think such a place would be anathema for anything else, but in fact there is not one but two populations of stars there! Seen in this Hubble image, there is a large cluster of bright blue stars surrounding the galaxy's black hole, which apparently formed there about 200 million years ago. Surrounding that is a ring of older, redder stars, appearing to give Andromeda two nuclei. Stars orbiting black holes are not too surprising - we see that in our own galaxy - but it's not at all clear how those blue stars could've formed so close to that monster in the middle. Hubble observations like this one will hopefully help us understand and eventually solve that mystery.

The lumpy dark

Dark matter is a substance about which we know very little. We know more about what it isn't: it can't be dead stars, rogue planets, or wandering black holes, for example. For various reasons, every kind of normal matter has been eliminated from the list, leaving some form of exotic matter that isn't well understood.

But that doesn't mean we know nothing: we actually can map its location on the sky! As light from distant galaxies passes through dark matter, the gravity of the invisible material bends that light, distorting it - this is called a gravitational lens. The bigger the warp, the more dark matter must be there. The Canada-France-Hawaii Telescope Lensing Survey observed over 10 million galaxies, looking for that subtle distortion, and made dark matter maps of four regions on the sky. The result is the image above. For comparison, it includes the full Moon for scale, as well as the largest dark matter map previously made.

Large scale maps of dark matter like this are critical for understanding its distribution, and for figuring out what the heck this stuff is. As it happens, detectors on board the Fermi spacecraft as well as underground in the Large Hadron Collider are on the hunt for the weird particle constituents of dark matter. Very soon, we may know quite a bit more about it.

The green apple cosmos

The Sloan Digital Sky Survey is an amazing project: map out the positions and colors of objects in the sky to high precision. In the case of galaxies, the colors can be use to get a decent estimate of the distance; galaxies moving away from us as the Universe expands get their colors subtly changed versus distance.

Using this data covering an incredible 1/4 of the entire sky, astronomers created the map above of 900,000 luminous galaxies: ones that are brighter than usual. By choosing these overachievers they can see them at great distances, and make a complete map. This map, the largest ever compiled, shows each galaxy as a single green dot, and stretches out to a distance of 6 billion light years -- halfway across the Universe. The galaxies can be seen to cluster in some spots, and this tells us about conditions in the early cosmos when these clusters formed. Astronomers using these data have constrained limits on such disparate things as dark energy and neutrino mass!

They also put together a very cool video where they move the data around in 3D. It's mesmerizing... especially when you think that to do this in real life you'd have to travel at trillions of times the speed of light!

Primo Supernova

Hubble has bagged the most distant Type Ia supernova ever to have its distance confirmed: dubbed SN Primo, the light we see left it a staggering 9 billion years ago!

It was found as part of an ambitious project using Hubble to look for such distant explosions in the near infrared, and is the first one found in the three-year survey. The project is being led by my old pal (yes, I'm bragging) and Nobel Prize winner Adam Riess, who has long been working with supernova to understand the expansion of the Universe. These types of exploding stars tend to explode in a manner that makes their distance relatively simple to calculate (well, once you've solved a host of problems first, which Adam did, which is why he won the Prize). And since they can be seen at vast distances, this makes them very useful for determining the overall shape and evolution of the Universe.

The top pictures shows the Hubble Ultra Deep Field; nearly everything you see in it is a far-flung galaxy. The boxed region is expanded on the bottom; on the left is one image of it and on the right another taken at a later time. The supernova wasn't there in the first image, but can be seen in the second. Adam's team will continue to use Hubble to look at this region over and again, looking for the tell-tale bright spot that marks the location of a new supernova.

By doing this they will improve our measurements of how the Universe is expanding, including the bizarre acceleration of the expansion discovered - in part by Adam - in 1998. I'll be very interested to see what else they find over the next few years of this project.

The WISE King and Queen

NASA’s Wide-field Infrared Survey Explorer (WISE) mapped out the entire sky in the far-infrared for about a year. Since it was a survey instrument, it didn't take pictures per se, instead counting infrared photons, noting their position, time, and energy. This allows astronomers to make a mosaic image of any size... so they created this astonishing map of the constellations Cassiopeia (the Queen) and Cepheus (the king), covering over 1000 square degrees of sky! For comparison, the full Moon is about 1/5 of a square degree: this map covers the equivalent of 5000 full Moons!

There is no way I can convey the sheer depth and breadth of this image in the 610 pixel width of this blog, so you should download the crazy huge 70 Mb 13530 x 4609 pixel version. You can then sweep over the dust, gas, stars, cavities, shells, supernova remnants, and everything else littering this picture. It's breath-taking. To give you a hand, red colors are from very cool dust, green tends to come from complex organic molecules, and blue from warmer dust and gas.